RT leaves parts of the image with different noise levels

[Alex_M]

I use RT CUDA as production render for a job here and I noticed that it leaves a part of the image with different noise levels when renders finish. I didn't stop the render manually and there was no time limit. The only limit for RT was the noise threshold. Is this normal and can I prevent it? I never get these differing noise level lines with Vray Adv.

Please check the screenshots below (2nd one is enhanced to better see the noise difference).

[radoslav.platikanov]

Is the cleaner area around the center of the image? If so, this is a known issue, but we're not quite sure how to deal with it yet. I guess this is with a high noise threshold? It shouldn't be visible with more samples.
As a workaround, you can try setting the noise threshold to 0 and using a time limit. You'll probably need to run this command in the MAXScript listener too:

renderers.current.v_ray_settings.progressive_dynnoisethreshold=0

Another option is to use a lower number of rays per pixel. This will probably make the difference less visible, but it may decrease the performance.

[Alex_M]

Thanks for the workaround. I might try it out.

Yes, this is visible around the center of the image. It's pretty much in the shape of a square. It's like RT stopped refining the image midway instead of waiting for the pass to reach the borders of the image before it stops. It's visible mostly on images that I haven't waited long enough to get refined because the noise differences in the old and new passes is still large. If I have it refine for longer I'm sure it won't be that much visible, if at all.

[radoslav.platikanov]

Yes, it shouldn't be visible at all on final renders. The workaround is only for quick draft renders.